Statistics Definition and 998 Threads

Homework Statement Before I get started here I have one really quick basic question: Lets say I want the probability that an survives two hours, and that the probability an engine will fail in any given hour is .02. Then I can get 1 - .02 - .98(.02) = .9604. This is found by a geometric...

I have two different problems involving Tchebysheff's Theorem. Hopefully there isn't a rule about asking two different questions in one post. Number 1 Homework Statement The US mint produces dimes with an average diameter of .5 inch and a standard deviation of .01. Using Tchebysheff's...

Homework Statement The diameter of a shaft in an optical storage drive is normally distributed N(μ,σ2). The drive specifies that the shaft be 0.2500 ± 0.0015 in. Suppose μ= 0.2508 in and σ = 0.0005 in. What fraction of shafts conform to the design specifications? The Attempt at a...

Homework Statement An airline flies the same route at the same time each day. The flight time varies according to a Normal distribution with unknown mean and standard deviation. On 15% of days, the flight takes more than an hour. On 3% of days, the flight lasts 75 minutes or more. Use this...

If the probability density of X is given by f(x) = {2(1 − x) for 0 ≤ x ≤ 1 {0 otherwise (a) Find the probability density function of Y1 = 2X − 1. I do not know how to start this problem can someone please help. Is there a formula that I am missing from my notes to solve this problem?

Homework Statement 1) Let X have the p.d.f f(x) = 3(1-x)2, 0≤x<1. Compute: a) P(0.1 < X < 0.5) etc... 2) Find the mean and variance, and determine the 90th percentile , of each of the distributions given by the following densities: a) f(x) 2x, 0≤0<0 etc.. 3) Find the 50th...

Homework Statement Let X have a gamma distribution with parameters α and β. Show that P(X ≥ 2αβ) ≤ (2/e)2 Homework Equations f(x) = pfd of a Gamma The Attempt at a Solution I began by solving for P(X ≥ 2αβ) by doing ∫ f(x) dx from 2αβ to ∞ I set y=x/β for substitution. and I...

I am sooo lost in this class, please help. 1. Let the true (population) model be y = B0+B1x1+B2x2+u where u is an unobserved error term with u (conditional) x1, x2 and N(0, sigma^2). Hence, u is normally distributed with mean 0 and variance sigma^2 (i.e., E[u (conditional) x1, x2] = 0 and V...

Statistics: geometric distribution "proof" problem Homework Statement If Y has a geometric distribution with success probability p, show that: P(Y = an odd integer) = \frac{p}{1-q^{2}} Homework Equations p(y)=p(q)^{2} The Attempt at a Solution p(1)=pq^0 p(3)=pq^2 p(5)=pq^4...

Homework Statement On average, 2.5 telephone calls per minute are received at a corporation's switchboard. Making appropriate assumptions about the distribution ( provide justification ), find the probability that at any given minute there will be more than 2 calls. Homework Equations No...

Peter and Alex plays tennis. Peter serves through out the first game, Alex serves throughout the second game. When Peter serves, the probability that he wins is 0.8. When Alex serves first the probability that Peter wins is 0.4. A game cannot be drawn. After 6 games Peter and Alex both have won...

Homework Statement Let c be a constant, and define Y_{i}=1 if X_{i}\leq c and zero otherwise. Find a statistic that is a function of Y_{1},Y_{2},...Y_{n} and also unbiased for F_{X}(c)=\Phi\left(\dfrac{c-\mu}{\sigma}\right). Homework Equations The Attempt at a Solution not even...

Homework Statement Delegates from the G8 are to be seated around a circular table. How many different seating arrangements are possible if the French and Canadian delegates are to be seated next to each other, but the Russian and Japanese are not to be next to each other? Homework...

Hi all, I am working with long term potentiation (LTP) induction in hippocampal brain slices. I am wondering about how exactly to statistically analyze the data I am presented with. It looks like http://hmg.oxfordjournals.org/content/19/4/634/F5.small.gif Where each line of points...

Hello, I am struggling to find a suitable statistic test for one of my studies: I have 4 different conditions, and I want to test if my results differ on those conditions. When the dependent variable is continuous it is easy to find a statistical test; however when it is a categorical variable...

Homework Statement The eating club is hosting a make your own sundae at which the following are provided: Ice cream flavors: chocolate, cookies-n-cream, strawberry, vanilla Toppings: caramel, hot fudge, marshmellow, m & m's, nuts, strawberries a) How many sundaes are possible using...

To be honest I have no real idea how to do this. I know of the probability density function, and the cumulative probability function, but using them is another difficulty I'm trying to overcome. My questions are, Intravenous fluid bags are filled by an automated filling machine. Assume that...

Hello folks. This was in my exam and I wasn't sure how to solve it. Homework Statement A sample of 67 respondents was taken collectively by a population of 6,456 units. The number of those who said they were available to implement a development program were 35. To implement the program...

Homework Statement A Fisher presents the following data, which give the logarithm to the base 10 of the volume occupied by algal cells on successive days, taken over a period for which the relative growth rate is approximately constant. Day 1 = 3.592, Day 2 = 3.823, Day 3 = 4.174, Day 4 =...

Homework Statement Let k\geq1. Show that, for any set of n measurements, the fraction included in the interval \overline{y}-ks to \overline{y}+ks is at least (1-1/k2). [Hint: s2 = 1/(n-1)[\sum(yi-\overline{y})2]. In this expression, replace all deviations for which the absolute value of...

1. What is the expectation value, <x>, for the given distribution over the interval from – to + infinity of the function: f(x)=e^(-.5(x-mu)^2(sigma^-2)) 2. This is a statistics problem i think. I just need to know how this type of problem is worked out because it is relevant to my...

I want to know what is the meaning of percentile. what is the percentile : 23.79 means? Please give me explanation and also examples. Thanks!

Please teach me this: The general effort is to quantize the fields of elementary particles and gravitons.But I wonder about ''mathematical'' fields such as the fluctuation fields in statistical physics.I think there may be many ''continuous'' fields in physics.Could the functional integral...

Homework Statement For a system in equilibrium at temperature T, the probability of finding it in a microstate m is: P(m) = (1/Z)exp(-E/kT) where Z is the partition function. There are three accessible microstates, two with energy E_{a} and one with energy E_{b}. Two identical and...

I am finished with the first bachelor year at Computer Science and the next courses are: Assembly, Linear Algebra, Statistics, Java. Many people from my class said that they will not take Statistics as it's not that helpful to them and I was thinking of how accurate that is. Is Statistics...

Could anyone give an insight as to how difficult a statistics major is? My college doesn't offer any probability classes until the junior year, so I'd have no way of knowing what it's like until then. My fear is that I'll wind up taking all these prereqs and end up hating or not understanding...

Homework Statement (a) A survey on 50 claims for a particular class of customers of a motor insurance company found out that the average cost for car damage is £700 with a standard deviation of 400. The insurance manager believes instead that the average cost is £80 bigger. (i) Does the...

Statistics and integration problem (urgent) can anyone help me with (6)?

Homework Statement Not really a homework problem, but something that I was curious about. I was thinking about how a calculator finds the area under the standard normal distribution, and I started to assume that it most likely has the antiderivative for the function that makes the standard...

I'm going to be a senior in high school next year, and I'm thinking about self-studying AP Statistics. I want to be some sort of mathematician or physicist, and I am thinking that having the equivalent of a first-year course in college statistics will significantly broaden my career choices and...

Hello, this is my first post in physics forum and I need some help in my future major selection. I plan to go into research in biology, and would like to go into computational biology in grad/med school (MD/PhD programs). I plan to double major in biochem and either math/statistics, and I will...

What book or course would you recommend to a beginner in Probability and Statistics? That is my question. However I would like to specify my intentions. Along my math courses I have observed (many people have) that mathematicians have a different way of thinking this common language...

Homework Statement Assume that the cholesterol level of college aged men nationwide is normally distributed with mean of 180 and standard deviation is 20. Twelve male MVCC students were randomly selected; the cholesterol level of each was determined: 250, 220, 145, 225, 170, 210, 200, 210...

Null Hypothesis/Alternative hypothesis, statistics help! Homework Statement For each of the following questions, state(using symbols) the null and alternative hypotheses. a.)Does the average speed of vehicles on the Thruway exceed 65? b.) Is the mean height of 6th graders different...

Homework Statement Suppose that the systolic blood pressure of 20 year old females is normally distributed with mean 120 and standard deviation 15. a.) What proportion of 20 year old females will have readings between 115 and 125? b.) If you selected a sample of 64 people from this...

Homework Statement You look at a random sample of 64 vehicles in one school parking lot and find that 24 are trucks. Determine the 80% confidence interval for the true population proportion of trucks in all the school lots. Homework Equations (work shown below) The Attempt at a...

Homework Statement Glucose level is normally distributed, standard deviation is known to be 25 units; determine the sample size needed to be 95% confident that the sample mean and the true population mean differ by at most 4 units. Homework Equations (work shown below) The Attempt...

Homework Statement Assume the life expectancy of U.S. males is normally distributed with a mean of 80 years and a standard deviation of 5 years. What is the probability that a randomly selected male lives more than 86 years? Homework Equations (work shown below) The Attempt at a...

Homework Statement Assume that the population is normal with some unknown mean and standard deviation of 25. A sample size 400 is taken. The resultant sample mean is 67. a.) What is your best estimate for the value of the population mean? b.) What is the value of the standard error...

Probability Interval, statistics help! Homework Statement Assume that the population is normal with mean of 90 and standard deviation of 25. A sample of size 100 will be selected. a.) What is your best estimate for the value of the sample mean? b.) What is the value of the standard error...

Homework Statement Records show that 72% of basketball foul shots attempted are successfully made during practice. Today, each of the 10 members of the team gets a practice shot. What is the probability that at least 8 team members make the shot successfully? Homework Equations...

Homework Statement The probability that Joe owns a microwave oven is 75%; the probability that he owns a CD player is 45%; and the probability that he owns both is 40%. Find the probability that he owns either one but not both. Homework Equations (work posted below) The Attempt at...

Homework Statement Twelve colored ping-pong balls are placed into a shopping bag and well mixed. There are two red balls, six blue balls and four green balls. One ball is selected at random, its color noted and then it is set aside. A second ball is then randomly selected and its color...

Homework Statement An appliance store purchases electric ranges from two companies. From company A, 600 ranges are purchased, and 5% are found to be defective. From company B, 300 ranges are purchased, and 8% are found to be defective. Given that a range is defective, find the probability...

Homework Statement The number of defects in a sample of 20 parts is recorded for quality control purposes; over the last year the number of defects and their occurrence rate has been : 0 defects, 82%; 1 defect, 13%; 2 defects, 4%; 3 defects, 1%. Find the expected number of defects in the...

Homework Statement The probability of Mr. Jones being selected for jury duty is 70%. The probability that Mr. Smith will be selected is 40%. The probability that neither will be selected is 10%. What is the probability that both are selected? Homework Equations the "and" rule The...

Homework Statement In a certain high-risk group, the chance of a person having suffered a heart attack is 70%. If four persons are chosen from the group, find the probability that at least one will have had a heart attack. Homework Equations (work shown below) these would be dependent...

Homework Statement To test the efficacy of a new cholesterol-lowering medication, 10 people are selected at random. Each has their LDL levels measured (shown below as Before), then take the medicine for 10 weeks, and then has their LDL levels measured again (After). Before After...

T/F, Please Help! Elementary Statistics! Homework Statement 5-If a true-false exam contains 10 questions, there are 20 different ways to answer all the questions. Homework Equations There are none for it is a true false question. The Attempt at a Solution I believe this is...

Homework Statement (T/F) Subjective probability based on intuition and experience has little use in the real world. Homework Equations (no equations needed for it is T/F) The Attempt at a Solution I believe this is False because subject probability is probability derived from...